In this Paper, we analyse the changes in the risks of involuntary job loss in France between 1982 and 2002. We find that these risks are higher in the 1990s than they were in the 1980s. We develop an econometric analysis to separate the effects of institutional changes from the effects of new technologies. Our estimates show that the rise in job loss rates is significantly more pronounced in industries that have the largest share of R&D workers and the largest rate of new technologies’ users. These findings suggest that technological changes contribute to decreasing the incentive to keep workers for long period of time and to increasing job insecurity.job security; lobaour demand; seniority